A film formation device, such as a chemical vapor deposition (CVD) device or a physical vapor deposition (PVD) device, or a plasma etching device is used to form a semiconductor element. Such devices include a stage to hold a substrate (e.g., silicon wafer) in a depressurized processing chamber. One such stage is an electrostatic chuck including, for example, an electrostatic chuck (ESC) plate adhered to a base plate (base). Japanese Laid-Open Patent Publication No. 2009-152475 describes an electrostatic chuck plate incorporating an electrode, which is capable of attracting a substrate, and a heat generation body, which controls the temperature of the subject to be attracted (i.e., substrate). The temperature of the substrate attracted to an upper surface of the electrostatic chuck plate is adjusted by a cooling fluid, which flows through a conduit formed in the base plate, and the heat generation body, which is incorporated in the electrostatic chuck plate.
In the electrostatic chuck, the heat density may vary at the upper surface (substrate setting surface) of the electrostatic chuck plate that attracts the substrate. Such variation in the heat density causes variations in the temperature of the substrate. This may vary, for example, the etching rate of the plasma etching device and thereby lower the yield of the semiconductor element.